Semiconductor memory has become increasingly popular for use in various electronic devices. For example, non-volatile semiconductor memory is used in computers, tablets, digital cameras, and mobile computing devices. Electrically Erasable Programmable Read Only Memory (EEPROM) and flash memory are among the most popular non-volatile semiconductor memories.
The threshold voltage Vth is an important parameter in flash operations such as programming and erasing. Variations in threshold voltage can degrade performance or even lead to data errors. It is therefore desirable to have structures and methods for reducing variation in threshold voltage for non-volatile memories.